diff options
| author | Linus Torvalds <torvalds@linux-foundation.org> | 2026-02-01 10:47:21 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2026-02-01 10:47:21 -0800 |
| commit | c00a8791646a226b77d24980ffad0c5e8e268b07 (patch) | |
| tree | 68a0333e0c5fe15ee02375fc54b2571e71862538 | |
| parent | e53ada651abea14481336091fbe2428ff05a8eee (diff) | |
| parent | 76ed27608f7dd235b727ebbb12163438c2fbb617 (diff) | |
Merge tag 'perf-urgent-2026-02-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull perf events fix from Ingo Molnar:
"Fix a race in the user-callchains code"
* tag 'perf-urgent-2026-02-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
perf: sched: Fix perf crash with new is_user_task() helper
| -rw-r--r-- | include/linux/sched.h | 5 | ||||
| -rw-r--r-- | kernel/events/callchain.c | 2 | ||||
| -rw-r--r-- | kernel/events/core.c | 6 |
3 files changed, 9 insertions, 4 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h index da0133524d08..5f00b5ed0f3b 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1776,6 +1776,11 @@ static __always_inline bool is_percpu_thread(void) (current->nr_cpus_allowed == 1); } +static __always_inline bool is_user_task(struct task_struct *task) +{ + return task->mm && !(task->flags & (PF_KTHREAD | PF_USER_WORKER)); +} + /* Per-process atomic flags. */ #define PFA_NO_NEW_PRIVS 0 /* May not gain new privileges. */ #define PFA_SPREAD_PAGE 1 /* Spread page cache over cpuset */ diff --git a/kernel/events/callchain.c b/kernel/events/callchain.c index 1f6589578703..9d24b6e0c91f 100644 --- a/kernel/events/callchain.c +++ b/kernel/events/callchain.c @@ -246,7 +246,7 @@ get_perf_callchain(struct pt_regs *regs, bool kernel, bool user, if (user && !crosstask) { if (!user_mode(regs)) { - if (current->flags & (PF_KTHREAD | PF_USER_WORKER)) + if (!is_user_task(current)) goto exit_put; regs = task_pt_regs(current); } diff --git a/kernel/events/core.c b/kernel/events/core.c index a0fa488bce84..8cca80094624 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -7460,7 +7460,7 @@ static void perf_sample_regs_user(struct perf_regs *regs_user, if (user_mode(regs)) { regs_user->abi = perf_reg_abi(current); regs_user->regs = regs; - } else if (!(current->flags & (PF_KTHREAD | PF_USER_WORKER))) { + } else if (is_user_task(current)) { perf_get_regs_user(regs_user, regs); } else { regs_user->abi = PERF_SAMPLE_REGS_ABI_NONE; @@ -8100,7 +8100,7 @@ static u64 perf_virt_to_phys(u64 virt) * Try IRQ-safe get_user_page_fast_only first. * If failed, leave phys_addr as 0. */ - if (!(current->flags & (PF_KTHREAD | PF_USER_WORKER))) { + if (is_user_task(current)) { struct page *p; pagefault_disable(); @@ -8215,7 +8215,7 @@ perf_callchain(struct perf_event *event, struct pt_regs *regs) { bool kernel = !event->attr.exclude_callchain_kernel; bool user = !event->attr.exclude_callchain_user && - !(current->flags & (PF_KTHREAD | PF_USER_WORKER)); + is_user_task(current); /* Disallow cross-task user callchains. */ bool crosstask = event->ctx->task && event->ctx->task != current; bool defer_user = IS_ENABLED(CONFIG_UNWIND_USER) && user && |